The present invention relates to a word processing machine provided with a display device for displaying lines of text in a line-by-line manner.
German Offenlegungsschrift [Laid-open Application] No. 2,742,992 discloses a word processing device which includes a display device for displaying a section of text. Text characters fed in via a keyboard are displayed in succession in a character input position disposed on the right-hand side of the display device and are shifted to the left by one position with the input of every new character so that the last character fed in is always visible in the extreme right-hand position of the text display region of the display device and the entire text display region shows always the last fifteen, for example, characters fed in. The word processor also includes a data memory in which the fed-in text is stored and from which it is read out and displayed on the display device in sections each composed of fifteen characters.
The display device is provided to afford an opportunity for the operator to correct input errors before the text is printed or to make changes in the text. For this purpose, the text, which is displayed on the display device, must be shifted to the right to such an extent as to bring that part of the text to be corrected or amended in the character input position on the right-hand side of the display device. Special input means are available to the operator for shifting the text and for the various correction and editing procedures. There also exists the possibility of calling out a text contained in a data store and to shift it on the display device until the portion of the text which is to be changed comes to lie in the character input position.
If for purposes of correction a text has been fed in and the portion thereof to be changed has been shifted to the right into the character input position, the text following the portion to be corrected, i.e. the text which had previously been seen on the display device to the right of the portion to be corrected, is no longer visible to the operator. Corrections or editing measures therefore become difficult because the operator cannot see and control the portion of the text to be corrected in context with the text surrounding it. As a result, a typographical error, for example, can be detected only after viewing the entire word or at least the next-following character.
This drawback produces a particularly difficult situation if part of the text, e.g. a word, must be inserted or erased. In this case, the operator will generally have to make a hand-written note because during the correction he does not have a contiguous overview of the text on the display device.